1. Field of the Invention
The present invention relates to a belt-type continuously variable transmission incorporated into a vehicle. Particularly, the present invention relates to a structure of a case of the belt-type continuously variable transmission.
2. Description of the Related Art
U.S. Patent Application Publication No. 2010/0167853 discloses a conventional V-belt-type continuously variable transmission (CVT) built into a utility vehicle. In the continuously variable transmission disclosed in this literature, a fixed sheave of a drive pulley or a fixed sheave of a driven pulley is provided with fins which function as a centrifugal fan, and air introduced from outside into a case is caused to flow through the drive pulley and then the driven pulley, thereby cooling these pulleys and a V-belt.
The case of the continuously variable transmission includes a case body fastened to a crankcase of an engine and a cover joined to the case body. An air-intake duct is mounted to a peripheral wall of the case body in the vicinity of the drive pulley, while an air discharge duct is mounted to the cover of the transmission case in a vicinity of the driven pulley.
Since the air discharge duct is mounted to the cover of the transmission case in the conventional CVT as described above, the air discharge duct must first be detached and then the cover must be detached, when the case is opened for the purpose of maintenance. This is messy work. In addition, since the cover tends to have a substantial thickness, a relatively wide space is needed in front of the cover in a direction in which the cover is detached, when the cover is detached. This increases wasted space in the vehicle.